Electronic musical instrument

ABSTRACT

An amplitude of a basic musical tone waveshape at each of its sample points is formed by multiplying an amplitude of a tone color waveshape at each of its sample points by a digital signal representing the position of corresponding tone lever and accumulating the products of such multiplication. The amplitudes of the basic musical tone waveshape at the respective sample points are successively written in an analog waveshape memory and stored therein. A musical tone waveshape signal is obtained by reading from the analog waveshape memory the amplitude at a same point corresponding to an address signal formed by accumulating an F number of the selected key for a predetermined period.

United States Patent 11 1 Kondo et al. Sept. 9, 1975 [541 ELECTRONICMUSICAL INSTRUMENT 3.789.719 2/1974 Maillet 84/1113 X 3,794,748 2/1974Dcutschm. 84/124 [751 Inventors: Nakada}; 3.809.786 5/1974 Deutsch84/101 Masanob" (3hfbana; Tsuyosl" 3,821,714 6/1974 Tomisawa et111...... 84/10] x Futamase; Aklyoshi y all Of 3.2121390 7/1974 Tomisawaet a1... 84/].01 x Hamamatsu, Japan 3,836,909 9/l974 Cockcrcll 84/11)! X3,844,379 10/1974 Tomisawa et a1... 84/101 [73] Ass1gnee: Ni on Gakki 91Kabush'k' 3,854,365 12/1974 Tomisawa ct a1 84/101 Kaisha, Japan [221Filed: Mar. 6, 1974 Primary Examiner-Stephen J. Tomsky AssistantExuminerStanley J. Witkowski 21 A l. N 448,583 1 pp 0 Attorney, Agent,or Firm-Lamas Parry, Von Gehr,

Goldsmith & Deschamps [30] Foreign Application Priority Data Mar. 8.1973 Japan 48-27516 ABSTRACT [52] US. Cl. 84/l.0l; 84/109; 84/127 Anamplitude of a basic musical tone waveshapc at [5 1] Int. Cl. GIOH 1/02;GlOH 5/00 each of its sample points is formed by multiplying an [58]Field of Search 84/l.Ol-l.03, amplitude of a tone color waveshape ateach of its 84/l.l3, 1.24, 1.26, 1.28. DIG. 29, 1.09, 1.1, sample pointsby a digital signal representing the posil.27 tion of corresponding tonelever and accumulating the products of such multiplication; Theamplitudes of the [56] References Cited basic musical tone waveshape atthe respective sample UNITED STATES PATENTS points are successivelywritten in an analog waveshape 360799 0/1971 Watson 84/ m memory andstored therein. A musical tone wave- .imulsos 10 1971 watson ct allilu.II 144M211 x Shape signal is Obtained by wading from the analog3.683.096 11/1972 Peterson ct a1... 84/].03 x p memory the amplitude at9 same point COP 3 1971161 10 1972 D ch 4 1 1 responding to an addresssignal formed by accumulat- 3,743.7S5 7/1973 Watson S4/L0l ing an Fnumber of the selected key for a predeter- 3,746,773 7/1973 Vctrccht....84/101 mined period. 3,749.837 7/1973 Doughty 84/101 X 3.755.608 8/1973Deutsch 84/l.0l 4 Claims, 13 Drawing Figures BOARD CIRCUIT LOGIC CIRCUITl g 1 mass LEVER vIORY '@\l f 1 (LAN ADDRESS 4 5 TONE oowAmsoN a AYCOLOR SELECT'ON -s GENERA'DR MEMOQY CIRCUT LOGIC 7 mos CIRCUIT G GATEAGUMU MEMORY 1 LATOR I I ATTACK-DECAY S R FACTOR MULTlPLIER HOLD ClRCUlTPATENTEDSEP" 91915 SHEET 1 BF 8 Fl G. I

KEY BOARD cmcun I LOGIC CIRCUIT 3 U L M E I%IRE$M MEMORY GEN- 1 K (LAIMADDRESS 4 1 5 SEQ? TONE g2 g l a FACTOR COLOR LEC -6 GENERATOR MEMORYCIRCUIT I0 I l m i I 1 ANALOG DNA 06 GATE ACCUMU MEMORY LATOR T ATTACKDECAY B SAMPLE HOLDING FACTOR MULTIPLIER CIRCUIT FIG. I I

FROM 2 (AND GATE 5 q SAMPLE PULSE BUFFER LAMP. I44

PATENTEB SEP 9i975 SHEET 3 OF 8 Fl G. 3 0

T0 LOGIC CIRCUIT 2 M f I? I TONE g5 EEYJ N TER c0 INTER (TONE MAS EROOLOR CLO K MEMORY To CLAIM ADDRESS ADDRESS (IJMPARISCN AND COUNTERSELECTION l CIRCUIT 6 ADDRESS -18 COMPARATOR DECODER MEMORY QBCUIT \9 7MULTIPLIER E AmLMLAT -22 MASTER 0R CLOCK TOGATEII f ED GATE NW MEMORY'PATENTEI] SEP 91975 sum 0f 3 TO MULTIPLIER 2| 2 m u P .U W m PATENTEDSEP 9 I975 sumsu g FIG. 6

TO MEMORY IO M FIG. 7

OUTPUT INPUT 'PATENTEDSEP 'r 3 903 775 sum 6 5 3 FIG. 8

ATTACKn 1 INVERTER S lNvz U CM *l AD] ADDER 1 ADDER Mu NULTIPLIER MUZMLTIPLIER ATTACK DECAY SELECTION GATE 5G2 SELCT U T0 MULTIPLIER 2|PATENTED 93% 3. 903 775 SHEET 8 BF 8 FIG. IO To] 32 TO 4 BYNARY 1 r33 s4CHANEL W 2 ADDRESS FROM 8 COUNTER WTER COUNTER t LAS F CR NUMBER rDECODER SANPLE RESET PULSE PULSE T0l4 TOI3 K i W 25 \1 NEW SELECT mmCLAIM GATE -35 Y FROM? 26 RHEASE 2? KEY -36 29 ADRRESS CLAM -28 w ATTACKosc 3 5| DECAY 49 -69 DECAY osc WW 9 ii 52 56 TO 5 ,A f 54 s 4 W GATEczLggsT i F5 EGISTER A B Q CR CR ELECTRONIC MUSICAL INSTRUMENTBACKGROUND OF THE INVENTION This invention relates to an electronicmusical instrument and, more particularly, to an electronic musicalinstrument in which a basic musical tone waveshape is formed inaccordance with a plurality of tone color waveshapes and positions of aplurality of tone levers and written in an analog memory for subsequentrepetitive reading therefrom at a period selected by depression of a keyto produce an electrical musical tone waveshape output.

In prior art electronic musical instruments, tone source signals areproduced by a plurality of oscillators or frequency dividers and thesetone source signals are applied to a tone color circuit via a key switchto produce a desired musical tone waveshape. The prior art electronicmusical instruments therefore require a very complicated and largecircuit construction.

SUMMARY OF THE INVENTION It is, therefore, an object of the presentinvention to eliminate the above described disadvantages of the priorart electronic musical instrument and provide a novel electronic musicalinstrument which, despite its relatively simple construction, is capableof accurately producing a desired musical tone waveshape signal.

It is another object of the invention to provide an electronic musicalinstrument constructed on a principle which is entirely different fromthat of the prior art and requiring no more than a simple shift registertype analog memory as a memory for producing various kinds of musicaltone waveshape signals.

It is another object of the invention to provide an electronic musicalinstrument capable of producing a sample point amplitude of the basicmusical tone waveshape for each of a predetermined number of samplepoints by sequentially multiplying the respective voltage levels at eachsample point of a plurality to tone color waveshapes with digitalsignals representing positions of respective tone levers and thereafteraccumulating the results of the multiplication thereby to produce thebasic musical tone waveshape from the analog memory without requiring acomplicated calculation.

It is another object of the invention to provide an electronic musicalinstrument capable of immediately producing a desired basic musical tonewaveshape corresponding to positions of tone levers by adjusting thepositions of these tone levers.

It is another object of the invention to provide an electronic musicalinstrument capable of producing from a single memory a plurality ofmusical tone signals of different tone pitches corresponding todepressed keys by reading out a basic musical tone waveshape amplitudeat a sample point corresponding to a claim address signal which isformed by accumulating an F number corresponding to a depressed key by apredetermined number of periods.

It is another object of the invention to provide an electronic musicalinstrument capable of producing a musical tone signal provided withattack and decay envelopes corresponding to desired attack and decayfactors by adjusting the voltage level of an output musical tone signalby attack and decay factors consisting of digital signals.

It is still another object of the invention to provide an electronicmusical instrument capable of readily producing a compound tone musicaltone signal by accumulating in an analog manner the waveshape amplitudesread from an analog waveshape memory during a predetermined period oftime and outputting the result of the accumulation.

These and other objects of the invention will become apparent from thedescription made hereinbelow with reference to the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing onepreferred embodiment of the electronic musical instrument according tothe invention;

FIG. 2 is a circuit diagram showing an example of an analog accumulator;

FIG. 3a is a block diagram showing an example of a musical tonewaveshape writing logic circuit;

FIG. 3b is a diagram showing the tone color memory 7 in FIG. 3a more indetail;

FIG. 30 is a diagram showing the tone lever circuit in FIG. 3a more indetail;

FIG. 4 is a circuit diagram showing an example of an attack-decay factormultiplier;

FIG. 5 is a timing chart showing relations between a tone color memoryaddress counter, a tone lever counter and an analog memory addresscounter in writing a musical tone waveshape;

FIG. 6 is a circuit diagram showing an example of a waveshape writinggate; I

FIG. 7 is a diagram showing shifting of an amplitude voltage level ofeach bit of the musical tone waveshape to be written in an analogwaveshape memory;

FIG. 8 is a block diagram showing an example of an attack-decay factorgenerator 5;

FIG. 9 is a block diagram showing a keyboard circuit FIG. 10 is a blockdiagram showing a logic circuit 2; and

FIG. 11 is a circuit diagram showing a sample hold circuit 14.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. I, a keyboardcircuit 1 is adapted to pass a drive signal provided by a logic circuit2 to a contact of each key of a keyboard. If a selected key isdepressed, a timing pulse corresponding to the key is supplied to thelogic circuit 2 as key identification information. The logic circuit 2provides, upon receipt of this key indentification information, anaddress signal of the depressed key to a frequency memory 3. The addresssignal denotes which note of which octave the depressed key represents.The large thick arrows in FIG. 1, as well as in FIGS. 30, 8 and I0,indicate parallel transmission of muIti-bit signals, while the smallarrows indicate transmission of single-bit signals.

The frequency memory is a read-only memory in which are stored numericalvalues corresponding to frequencies of the notes of the respective keys.These numerical values are represented, for purposes of explanation, asF numbers."

For example, numerical values of F numbers corresponding respectively tofrequencies of notes ranging from C in the sixth octave (C.;) to C inthe seventh octave (C are shown in Table I.

Table I Table 2-Continued Note name Frequency F number Accumulated qFperiods C 2093.00 1.0000 5 A 3 n 1 A"; 12:23:22 8:331; 35 33:5; 5

A l7fit),(Xl (1.84l2 G lofil .22 0.7940 c 1567.9x 0.7494 \i The claimaddress signal is used not for directly read- F. 139091 0.6676 10 E 3 x5mg a waveshape analog memory 10 but for comparison o it l244-5l andselection of an analog memory address signal 5613 which is a valuecorresponding to data at each sample 1 10x13 0.520s C l046.5() 0.5000point of a musical tone waveshape stored 1n the waveshape analog memory10. A claim address comparison and selection circuit 6 is adapted toperform such com- In the frequency memory 3, an F number correparison dSelection spohdlhg to the address Signal pp from the logic it should benoted that each claim address signal is an Circuit 2 is Selected andProvided to a claim address address signal forarespective sample pointof a desired generator 4. in the claim address generator 4, values 0fmusical {one waveshape whereas each analog memory the F number arecumulatively added in accordance 2O address signal is an address signalfor a respective sam- Whh Pcriod '1 designated y lhc logic Circuit 2 andple point of a musical tone waveshape which is actually eachcumulatively added value denoted qF is outputted ff d as a claim addressignal- When the claim address signal and the analog mem- Cumulativelyadd d alu s q are ShOWfl in Table 2 ory address signal coincide witheach other, the claim for #6 in the Sixth Octave) and C? take" addresscomparison and selection circuit 6 produces a for illustrative purposeS.The SUCCeSSiVc Values Shown control signal causes a musical [onewaveshape for each in Table 2 are repeatedly Produced as selection gate11 to open. This musical tone waveshape Claim Bddl'CSS signal Whil hekey correspon ing to selection gate 11 is an analog gate provided forselectthat note remains depressed. The qF value f0! 5116- ing a voltagelevel V concerning one sample point of cessive accumulated periods inTable 2 varies in the musical tone waveshape of the currently depressedaccordance with a simple arithmetic progression. key from the analogwaveshape memory 10. The tone Thus, each note column in Table 2 has asequence of color memory circuit 7 comprises a plurality of tone qFterms each of which differs from the preceding color memories each ofwhich stores a particular tone term by the same F number. Therefore, theqF term color waveshape by storing amplitude samples thereof for anyaccumulated period can be determined from at respective sample points.Upon receipt of signals the equation: qF= F+ (period number l)F. from alogic circuit 8, the amplitude at the first sample Table 2 point of thefirst tone color memory is initially read out.

Then the amplitude at the first sample point of the sec- Accumulmcd qFond tone color memory is read out, and reading in a pcriuds like mannersuccessively contmues. When the ampli- G tudes at the first samplepoints of all the tone color I (mg I 3 L000) memories have been readout, the amplitude at the secl.7826 2.0000 ond sample point of the firstmemory is read out, fol- Z i lowed by the amplitude at the second samplepoint of 5 51, 55 5 the second memory, and so on. In the analog wave- 65.3478 6 shape memory 10 there is stored a musical tone waveshape whichis produced by combining tone color waveshapes, each level of which isdetermined by a tone lever circuit 9, as will be described in detaillater. The output of the musical tone selection gate 11, i.e. themusical tone waveshape signal of the depressed key 31 27.6303 31.0000 332852' 32000, is represented by the voltage Vi. This output is applled 3329.4129 33.0000 to an attack-decay factor multiplier 12 and multipliedwith attack and decay factors for producing a musical 36 32.0868361.0000 tone waveshape signal. The attack and decay factors are formedby the attack-decay factor generator 5 as will be described in detaillater with references to FIG. 8. The output of the attack-decay factorsmultiplier 12 y is a level of a single tone represented by the voltageVi. A musical tone waveshape signal of a compound tone is produced byapplying the above described musical tone waveshape signal multipliedwith the attack and decay factors to an analog accumulator l3 andcumulatively adding voltage levels Vi for l2 notes (Not necessarilynotes of one octave but any note will suffice.) 6 6213010 When analogaccumulator 13 has completed this cumulative addition for the 12 notes,the voltage levels which have been cumulatively added together areapplied to a sample holding circuit 14 in response to a signal fromlogic circuit 2 and are held in the holding circuit. Thereupon. analogaccumulator 13 starts a new adding operation and holding circuit 14continues to hold the previously added voltage levels until completionof the new adding operation and, upon such completion, receives andholds the new output of analog accumulator 13.

FIG. 2 is a circuit diagram of one example of the ana log accumulator13. In the figure, reference character I designates a voltage-currentconverter, C a capacitor and S a reset switch respectively. The resetswitch S may actually be composed of electronic components but in thisfigure it is shown simply as a mechanical switch. Reset switch S closesupon receipt of a reset signal from logic circuit 2 and thereby causescapacitor C to discharge. Reset switch S opens when no reset signal isapplied thereto. While reset switch 5 is open, capacitor C issuccessively charged with the outputs of multiplier 12, therebyeffecting accumulation of the voltage levels of the i2 tones. When theaccumulation has been completed, a sample pulse is applied from logiccircuit 2 to sample holding circuit 14. Consequently, holding circuit 14is actuated to cause a voltage level of capacitor C corresponding to theaccumulation of the voltage levels of the 12 tones to be shifted toholding circuit 14 and held there until the next sample pulse isapplied. Immediately after the application of the sample pulse toholding circuit 14, a reset pulse is applied for an instant toaccumulator 13 thereby causing switch S to close and capacitor C todischarge in preparation for the next accumulation. The compound tonemusical tone waveshape signal thus sequentially provided from sampleholding circuit 14 constitutes one sample point amplitude of the musicaltone waveshape to be produced.

Next to be described is the musical tone waveshape writing logic circuit8 one example of which is shown in a block diagram in FIG. 30. FIGS. 3band 3c show the tone color memory 7 and the tone lever circuit more indetail.

Clock pulses generated by a master oscillator M (FIG. 3a) are applied toan analog memory address counter 15. Carry pulses of the counter 15 areapplied to a tone lever counter 16 and carry pulses of the counter 16 toa tone color memory address counter 17. The analog memory addresscounter 15 has a capacity of 6 bits and is adapted to sequentiallyoutput the analog memory address signal of 64 words at a high rate. Ashas previously been described, the analog memory address signal iscompared with the claim address signal in the claim address comparisonand selection circuit 6. The tone lever counter 16 outputs data of n 1words (where n represents the number of the tone lever switches providedin tone lever circuit 9 for selecting a desired one or more of aplurality of tone colors of various musical instruments) at a rate whichis l/64 that of the analog memory address counter 15.

The outputs of the tone lever counter 16 corresponding to the n wordsare decoded by a decoder to drive the tone lever circuit 9. The outputcorresponding to the last word is applied to a timing control logiccircuit 19 for causing it to produce a write signal WR to be describedlater.

The tone color memory address counter 17 has a capacity of 6 bits and isadapted to output data of 64 words at a rate which is that of the tonelever counter 16. The output of this counter 17 is used as an addresssignal for reading data from the tone color memory circuit 7.

The tone color memory circuit 7 comprises n memories M M,, correspondingin number to the number of tone lever switches in tone lever circuit 9.In each of the n memories, :1 waveshape of the particular tone color isstored in analog representation at 64 sample points for one period. Theoutput from the tone color memory address counter 17 is used to read outdata at these 64 sample points.

The decoded outputs corresponding to the n words are provided from thedecoder 20 to the tone color memory circuit 7 to drive sequentially then tone color memories M,M,,. The sample point read at this time isdesignated by the address signal from the tone color 'counter 17.

The outputs from the decoder 20 also drive the tone lever circuit 9thereby causing it to produce 2 bit digital signals representing thestates of the respective tone lever switches 5 -8,, through diode matrixD,-D,,.

The particular tone lever switch, e.g. the third tone lever switch Swhich is driven corresponds to the particular tone color memory which isbeing read at the same instant (i.e. the tone color memory M The tonelevers switches respectively have, for example, four states, i.e. 1, Va,A, and 0.

The states of the respective tone lever switches are multiplied with thedata of the corresponding tone colors in a tone lever state multiplier21 and a resulting output is produced therefrom as a voltage level. Theresult of this multiplication is applied to a tone color accumulator 22.If, for example, the throw-in state of a tone lever switch is O, theresult of the multiplication is O and, accordingly, no voltage level isoutput. States of the rest of the tone lever switches are successivelymultiplied with data of the corresponding tone color in the tone leverstate multiplier 21 and the results of multiplication are accumulated inthe tone color accumulator 22. As the above described multiplication andaccumulation are carried out with respect to all of the n tone levers, atotal sum of the accumulation is pro duced as the output of the tonecolor accumulator 22. This total sum is a voltage level representing onesample point of a musical tone waveshape composed of the n tone colors.

The above described operation is conducted within a period of timeduring which the tone color memory address counter 17 outputs one word.During this period the tone lever counter 16 outputs n words and theanalog memory address counter 15 outputs 64 X n words.

The word tone color" herein means a tone color of a musical instrumentsuch as flute or strings. The tone lever state multiplier 21 and thetone color accumulator 22 may respectively be of a similar constructionto that of the attack-decay factor multiplier 12 shown in FIG. 4 and theanalog accumulator 13 shown in FIG. 2, as will now be described more indetail.

In FIG. 4, Ri,-Ri,,, Rs -Rs and RE designate resistors, Tn-Trtransistors or field effect transistors and LSB-MSB, electronic switches(shown as mechanical switches for convenience of explanation). In casethe circuit shown in FIG. 4 is used as the tone lever state multiplier21, a voltage level Vi at a sample point in tone color memory circuit 7is applied to this circuit, whereas digital signals representing statesof the tone lever switches are applied from tone lever circuit 9 to therespective electronic switches LSB-MSB. In the embodiment of tone levercircuit 9 shown in FIG. 3c, the number of possible states of each tonelever switch S -S, is four, and these states can be represented by twobits. Consequently, the FIG. 4 circuit insofar as it relates to thetransistors Tr and Tr will suffice for the tone lever state multiplier21. Accordingly, the switches LSB and KSB respectively correspond to thetwo bits of each digital word supplied from tone lever circuit 9, andthe switches close when the bit is l and open when the bit is 0. Thetone lever state multiplier 2I therefore produces an output whichrepresents the state of the tone lever switch, i.e. the input level Vicontrolled according to the digital word.

When the tone color accumulator 22 has completed all accumulationconcerning one sample point of the musical tone waveshape, a waveshapewrite gate 23 is opened. Application of a waveshape write instruction Wto this gate 23 will be described hereinbelow with reference to FIG. 6.

In an address comparator 18, the analog memory address signal which isthe output of the analog memory counter 15 is compared with the tonecolor memory address signal which is the output of the tone color memoryaddress counter 17 and, when the two address signals correspond to eachother, an address coincidence signal SA is applied to an AND gate AND.In the meantime, the timing control logic circuit 19 provides a writesignal WR to the AND gate AND upon completion of accumulation for all ofthe tone lever switches and subsequently provides a reset signal ac tothe accumulator 22 upon completion of writing. FIG. 5 is a timing chartof the respective output data of the tone color memory address counterI7, the analog memory address counter and the tone lever counter 16.

While the tone color memory address counter 17 outputs one word, thetone lever counter I6 outputs n 1 words. While the tone lever counter 16outputs l word, the analog memory address counter 15 outputs 64 words.Time during which the tone lever counter 16 produces data for drivingthe first to the nth tone lever switches S -S is equal to time duringwhich the tone color accumulator 22 carries out accumulation of onesample point ofa musical tone waveshape with respect to the respectivetone colors. The (n l )th output data of the tone lever counter 16causes the timing control logic circuit 19 to produce the write signalWR. The coincidence signal SA representing coincidence of the tone colormemory address and the analog memory address is produced n 1 times inthe address comparator 18 while one word of the tone color memoryaddress is output. A coincidence signal SA effective for producing thewaveshape write instruction W is the (n +l )th one. The analog memoryaddress signal shown in FIG. 5 is for the analog memory address of 64Words which is produced when the tone lever counter counts the (n +1 )thoutput data.

While the tone color memory address counter is counting the address I,the coincidence signal SA is produced when the analog memory addresscounter also counts the address 1. Then while the tone color memoryaddress counter is counting the address 2, the coincidence signal SA isproduced when the analog memory address counter also counts the address2.

Thus, the AND gate AND produces its output only when the addresscoincidence signal SA and the write signal WR are simultaneously appliedto the AND gate AND. This output of the AND gate AND is the waveshapewrite instruction W which operates the waveshape write gate 23. FIG. 6is one example of a circuit construction of the waveshape write gate 23.

When the waveshape write instruction W is input, a MOS transistor M isactuated to cause the voltage level representing one sample point of themusical tone waveshape provided by the tone color accumulator 22 to beapplied to the analog waveshape memory 10 as a new waveshape data signalNW. Since the output of an inverter INV is 0 at this time, a MOStransistor M is not actuated and, accordingly, a memory waveshape datasignal MW fed back from the waveshape analog memory I0 is not passedthrough the waveshape write gate 23. Thus, the new waveshape data signalNW is selected in the waveshape write gate 23 and thereafter is storedin the analog waveshape memory IO. It will be apparent from theforegoing description that the waveshape data signal NW isrepresentative of the musical tone waveshape at one sample point andtakes into account the throw-in states of the tone lever switches.

Upon completion of writing of the data for one sample point, the tonecolor memory address counter 17 proceeds to the next address and repeatsthe above described operation to cause data for the next sample point tobe written in the waveshape memory I0. Thus, data for all of the 64sample points are sequentially stored in the waveshape memory I0 therebycompleting storage of one musical tone waveshape. If no waveshape writeinstruction W is input to the waveshape write gate 23, the output of theinverter INV is I so that the MOS transistor M is actuated. Accordingly,the memory waveshape data signal MW fed back from the analog waveshapememory 10 is applied to the analog waveshape memory I0 as the output ofthe waveshape write gate 23.

The analog waveshape memory 10 consists of an analog shift register suchas a CCD (charged coupled device) of the type described in Electronics,May II, 1970, pp. 1 12-1 18. The CCD has capacitors for 64 bits eachbeing capable of storing the voltage level at one sample point.Accordingly, the CCD is capable of storing voltage levels of 64 samplepoints in all. Writing of new waveshape data NW and storing of formerwaveshape data MW in the waveshape memory 10 are made possible byshifting the voltage level stored in each bit by one by application of amaster clock pulse produced from the master oscillator M. If the time atwhich the voltage level is shifted is represented as I, the state of theamplitude voltage level at each sample point stored in the respectivebits from I to 1 is shown in FIG. 7. FIG. 7 shows the change of contentsfor the respective bits in the analog waveshape memory 10.

The amplitude voltage level at one sample point of the musical tonewaveshape input to the analog waveshape memory 10 is first stored in thefirst bit thereof, shifted 64 times thereafter and output from the 64thbit. When there is no new waveshape data NW supplied from the tone coloraccumulator 22. the amplitude voltage level of one sample point of themusical tone waveshape output from the 64th bit is fed back to theanalog waveshape memory as the memory waveshape data MW and stored inthe first bit of the memory 10.

The period of application of the new waveshape data NW is equal to thecounting speed of the tone color memory address counter 17 whereasshifting speed by the master clock is much higher than the countingspeed of the counter 17. Accordingly, musical tone waveshape data fromthe memory 10 are constantly fed back to the memory 10 during theinterval of the new waveshape data NW fed to the memory 10. Further,data of one sample point of the same musical tone waveshape arerepeatedly read from the analog waveshape memory N) at a relatively highrate. Accordingly, a musical tone waveshape of a desired note can beproduced by adjusting the timing of selection of the data output fromthe analog waveshape memory 10. As has previously been described, thisselection is designated by the claim address signal produced upondepression of the key.

The musical tone waveshape in the analog waveshape memory 10 is selectedat the musical tone waveshape selection gate 11 and thereafter ismultiplied with the attack-decay factors in the attack-decay factormultiplier 12.

Next to be described the application of the attack and decay factors tothe musical tone waveshape. An address signal representing an attack ordecay envelope is applied from the logical circuit 2 to the attack-decayfactor generator 5. This address signal consists of 6 bits, one bit ofwhich is used for designating the attack envelope or the decay envelopeand the rest of the bits are used to designate 32 sample pointsconstituting the respective envelopes. These sample points start fromdepression of the key in the case of the attack envelope and start fromrelease of the key in the case of the decay envelope.

FIG. 8 is a block diagram showing one example of the attack-decay factorgenerator 5. The attack and decay factors are represented by voltagelevels of the envelopes corresponding to the attack-decay address signalsupplied from the logic circuit 2. The attack-decay factors are given bythe following equation using voltage level (dB) as unit. Attack factorwhere 5 represents dividing number. Decay factor (in cascn E K) where Krepresents the number ofa sample point of the decay envelope at whichthe envelope bends as it be gins to level off from its initial steepdescent.

The attack decay factor generator 5 shown in FIG. 8 is adapted toperform the above described calculation to produce the attack and decayfactors. The nth sample point n of the attack envelope is inverted to nby an inverted INV; and thereafter is added to the dividing number S ofthe attack envelope in an adder AD The output Sn of the adder AD, isapplied, on one hand, to an adder AD: where +l is added to Sn to producean output Sn+l. The output Sn is applied, on the other hand, to amultiplier MU The output Sn+l of the adder AD, is multiplied with theoutput Sn of the adder AD in the multiplier MU, to produce an output(Sn) (Sn+l This output of the multiplier MU is further multiplied withA/2 in a multiplier MU to produce The output An(dB) of the multiplier MUis input to a selection gate 86 The values S and A/2 are values whichare preset in the generator 5.

+1 in the adders AD, and AD is required because in the system accordingto the invention the complement of two is used in the requiredcalculation.

Calculation of the decay factor will be described with reference also toFIG. 8.

In a comparator CM, n and K are compared with each other for determiningwhich is a larger number. The output signal C of the comparator CM is 1if n is smaller than K (n K) and 0 if n is equal or larger than K (n 5K).

A value D n is produced through a multiplier MU whereas a value D,K D(nK) is produced through an adder AD a multiplier MU. and an adder AD Ifa signal representing the value D,n input to the selection gate SG isdesignated as A and a signal representing the value D K D (n'K) as B,the signal A is selected at the selection gate S0 when the signal C fromthe comparator CM is 1, whereas the signal 8 is selected when the signalC is O. The values K, K, D D and D,K are preset in the generator 5. Theoutput Dn(dB) thus obtained is applied to the selection gate SG Eitherone of values An or Dn is selected in ac cordance with an attack ordecay selection address signal from the logic circuit 2 and the selectedone is applied to the attack-decay factor multiplier 12 as the attack ordecay factor.

FIG. 4 shows one example of the attack-decay factor multiplier 12.Reference characters Ri Ri,,, RS,RS,, and RE denote resistors and Tr,Trn transistors or field effect transistors. Digital control switchesLSB-MSB are switches respectively provided for the output bits of theattack-decay factor generator 5. There are provided, for example, 7switches if the output An or Dn of the attack-decay factor generator 5is a binary word of 7 bits. The signal An or Dn is applied to thedigital control switches LSB-MSB. If, for example, the switch LSBcorresponds to 1 dB, the switch LSB only is closed when the signal A orD, is l dB and an attenuation output of l dB is obtained. Values ofresistance corresponding to the respective switches are selected so asto be suitable for obtaining the required attenuation. Moreover, if thesignal A,, or Dn is 2 dB, only the switch next to the switch LSB isclosed to produce an attenuation output of 2 dB.

The subsequent digital control switches are actuated according to thelevel (dB) of the signal applied thereto whereby a desired amount ofattenuation is obtained.

Since the multiplier 12 is of an attenuation type, the same resultproduced in the case of applying the signal An or Dn is also produced inthe case where the signal An or Dn is applied to the multiplier 12. ltwill therefore be appreciated that no change of sign is required formultiplier 12.

ln the meantime, the signal representing the musical tone waveshapecorresponding to the depressed key is applied to the input of themultiplier 12.

Consequently, a musical tone waveshape signal multiplied with the attackor decay factor is produced as the output of the multiplier 12. Itshould be noted that the foregoing operation is performed with respectto each of the l2 notes (not necessarily limited to one octave) in atime sharing manner in the system from the keyboard circuit 1 to theattack-decay factor multiplier 12. Finally, the voltage levels of the 12notes are cumulatively added together in the analog accumulator 13 and afinal output is produced from the sample holding circuit 14 as a signalrepresenting the compound musical tone waveshape at one sample pointcombined with specific tone color and the attack and decay factors.

FIG. is a block diagram showing a detailed circuit construction of logiccircuit 2 shown in FIG. 1. A shift register 25 has stages correspondingin number to the total number of the keys and receives the output of theOR circuit Or (HO. 9). Accordingly, the input to shift register 25represents the present state of the key and the output thereofrepresents the preceding state of the same key. An AND gate 26 producesa key new press signal which represents that a key has newly beendepressed and an AND gate 27 produces a key new release signal whichrepresents that a depressed key has been released.

A claim register 28 has stages (channels) corresponding in number to themaximum number of tones to be reproduced simultaneously, e.g. l2, eachstage storing a I bit when the tone of the corresponding channel isbeing reproduced.

A claimed key address shift register 36 stores a key address signalwhich identifies the depressed key in accordance with the bits stored inthe respective stages of register 28.

The output of the analog memory address counter (FIG. 3a) is applied toa binary counter 32 where it is divided in frequency by 2 and furtherdivided in frequency by 12 in a duodecimal channel counter 33. Thefrequency divided output thereafter is applied to a key address counter34. The output of key address counter 34 is applied to a register 36through a select gate 35. A release register 41 stores a 1 bitcorresponding to the channel for the released key upon receipt of theoutput of a comparator 39 which compares the output of counter 34 withthe output of register 36.

A counter constituted by a gate 43, an adder 44 and a 12 stage shiftregister 45 counts attack clock pulses from an attack oscillator 48 anddecay clock pulses from a decay oscillator 51. This counting is made onthe basis of the contents of the respective stages (channels) ofregisters 28 and 41. During decay counting, a channel which has amaximum count in its register 45 is detected by an oldest signalgenerator consisting of comparators 52 and 55, a register 53 and a gate54, and an oldest signal is produced from the oldest sig' nal generatorand supplied to AND gate 29 at the corresponding channel time. Thiscauses a new claim signal to be produced at a time corresponding to achannel in which decay has advanced further than any other channels.Thus, the contents of registers 28 and 36 are rewritten. The countingduring the attack time is stopped by the output of an attack finishlogic element 49 and the contents of the respective stages of registers28 and 41 are reset by the output of a NAND circuit 56 provided fordetecting decay finish.

The output (4 bits) of channel counter 33 is applied to a last number"decoder 57 which detects the last number 12 among 12 counted values.This output is applied to AND gates 58 and 59. The sample pulse from ANDgate 59 is applied to the gate of an analog switching element which maybe an FET. Since at this time analog accumulator 13 (FIG. 1) hasfinished accumulation of the amplitudes of each corresponding samplepoint for the 12 notes ranging from the first to the twelfth channels, acomposite amplitude voltage of one sample point of the synthesizedwaveshapes of the l2 notes is applied from accumulator 13 to a bufferamplifier 141. This composite amplitude voltage is sampled throughswitching element 142 rendered conductive by the aforesaid sample pulse,and the sampled voltage is charged into a capacitor 143 and heldtherein. The voltage is then outputted from capacitor 143 through abuffer amplifier 144 of high input impedance. After the sample pulse hasceased to be applied, a reset pulse is applied from AND gate 58 (P10.10) to analog accumulator 13 to reset the same.

What is claimed is:

1. An electronic musical instrument for producing an electrical musicaltone signal comprising:

a. a plurality of tone color memories, each storing a waveshape of aparticular tone color in analog representation at plural sample points;

b. a plurality of tone lever switches, each being provided fordetermining the level of a corresponding tone color waveshape;

c. means for reading sequentially the waveshapes from the tone colormemories at said levels for the respective tone color waveshapes;

d. means for accumulating waveshape samples of the respective tonecolors at each sample point;

e. a waveshape analog memory for storing the accumulated waveshapesamples at each sample point of the analog memory and shiftingcyclically the accumulated samples;

f. a claim address generator for generating claim addresses which changeat a rate related to the frequency of a tone to be generated; and

g. means for reading from said analog memory those samples among thestored accumulated samples that are designated by said claim addresses.

2. An electronic musical instrument as defined in claim I, wherein saidmeans for reading sequentially the waveshapes from the tone colormemories comprise:

a. a tone color memory address counter capable of producing addresssignals which successively read the amplitudes stored at the respectiveaddresses of all of the tone color memories commonly; and

b. a tone lever counter capable of drigin sequentially said tone colormemories while the tone color memory address counter is addressing oneaddress to the tone color memories; and wherein said means for readingsequentially the waveshapes from the tone color memories furthercomprise:

c. a tone lever position signal generator which. upon receipt of anenergizing signal, generates a digital signal corresponding to aposition of each of the tone lever switches;

d. a tone lever state multiplier for producing an analog output signalby multiplying the analog signals from the tone color memoriessuccessively with the tone lever position digital signals; and

e. a tone color accumulator for accumulating said analog output signalfor the same period of time during which the tone color memory isaddressed thereby to produce the amplitude samples of a wavcshape atcertain intervals.

3. An electronic musical instrument as defined in claim 1, furthercomprising:

a. gate means connected to the output of said tone color accumulator toreceive said accumulated sample signal at certain intervals at one inputterminal thereof and to the output of said analog memory at anotherinput terminal thereof;

b. an analog memory address counter for producing address signals forsaid analog memory;

c. a comparator for comparing the tone color memory address signal withthe analog memory address signal from the analog memory address counterand producing a coincidence signal when these signals coincide with eachother;

d. a timing control logic circuit for producing a write signal when thecount of said tone lever counter is maximum; and

e. an AND gate which provides a gate signal to said gate means when saidcoincidence signal and said write signal coincide with each other, saidgate means passing the accumulated sample from said tone coloraccumulator to the input of said analog memory upon receipt of said gatesignal and, in the absence of said gate signal, passing the output ofsaid analog memory back to the input of said analog memory.

4. An electronic musical instrument as defined in claim 3, wherein saidmeans for reading from said analog memory comprise:

a. a frequency information memory storing F numbers corresponding tofrequencies of the notes of respective keys;

b. circuit means for producing an address signal designating apredetermined F number in said frequency information memory upondepression of a selected key;

c. said claim address generator receiving the F number designated insaid frequency information memory and producing a claim address signalby successively accumulating the F number at regular intervals over apredetermined period;

d. a comparator circuit for comparing the claim address signal with theanalog memory address signal and producing upon coincidence of thesesignals, a coincidence signal; and

e. a gate circuit connected to the output of said analog memory andadapted to gate out the output of said analog memory upon receipt of thecoincidence signal from said comparator.

1. An electronic musical instrument for producing an electrical musicaltone signal comprising: a. a plurality of tone color memories, eachstoring a waveshape of a particular tone color in analog representationat plural sample points; b. a plurality of tone lever switches, eachbeing provided for determining the level of a corresponding tone colorwaveshape; c. means for reading sequentially the waveshapes from thetone color memories at said levels for the respective tone colorwaveshapes; d. means for accumulating waveshape samples of therespective tone colors at each sample point; e. a waveshape analogmemory for storing the accumulated waveshape samples at each samplepoint of the analog memory and shifting cyclically the accumulatedsamples; f. a claim address generator for generating claim addresseswhich change at a rate related to the frequency of a tone to begenerated; and g. means for reading from said analog memory thosesamples among the stored accumulated samples that are designated by saidclaim addresses.
 2. An electronic musical instrument as defined in claim1, wherein said means for reading sequentially the waveshapes from thetone color memories comprise: a. a tone color memory address countercapable of producing address signals which successively read theamplitudes stored at the respective addresses of all of the tone colormemories commonly; and b. a tone lever counter capable of driginsequentially said tone color memories while the tone color memoryaddress counter is addressing one address to the tone color memories;and wherein said means for reading sequentially the waveshapes from thetone color memories further comprise: c. a tone lever position signalgenerator which, upon receipt of an energizing signal, generates adigital signal corresponding to a position of each of the tone leverswitches; d. a tone lever state multiplier for producing an analogoutput signal by multiplying the analog signals from the tone colormemories successively with the tone lever position digital signals; ande. a tone color accumulator for accumulating said analog output signalfor the same period of time during which the tone color memory isaddressed thereby to produce the amplitude samples of a waveshape atcertain intervals.
 3. An electronic musical instrument as defined inclaim 1, further comprising: a. gate means connected to the output ofsaid tone color accumulator to receive said accumulated sample signal atcertain intervals at one input terminal thereof and to the output ofsaid analog memory at another input terminal thereof; b. an analogmemory address counter for producing address signals for said analogmemory; c. a comparator for comparing the tone color memory addresssignal with the analog memory address signal from the analog memoryaddress counter and producing a coincidence signal when these signalscoincide with each other; d. a timing control logic circuit forproducing a write signal when the count of said tone lever counter ismaximum; and e. an AND gate which provides a gate signal to said gatemeans when said coincidence signal and said write signal coincide witheach other, said gate means passing the accumulated sample from saidtone color accumulator to the input of said analog memory upon receiptof said gate signal and, in the absence of said gate signal, passing theoutput of said analog memory back to the input of said analog memory. 4.An electronic musical instrument as defined in claim 3, wherein saidmeans for reading from said analog memory comprise: a. a frequencyinformation memory storing F numbers corresponding to frequencies of thenotes of respective keys; b. circuit means for producing an addresssignal designating a predetermined F number in said frequencyinformation memory upon depression of a selected key; c. said claimaddress generator receiving the F number designated in said frequencyinformation memory and producing a claim address signal by successivelyaccumulating the F number at regular intervals over a predeterminedperiod; d. a comparator circuit for comparing the claim address signalwith the analog memory address signal and producing upon coincidence ofthese signals, a coincidence signal; and e. a gate circuit connected tothe output of said analog memory and adapted to gate out the output ofsaid analog memory upon receipt of the coincidence signal from saidcomparator.